Shape memory alloy actuators for aircraft landing gear

ABSTRACT

Shape memory alloy actuators for aircraft landing gear are provided. In one embodiment a retractable aircraft landing gear system is provided. This embodiment includes a shape memory spring strut having a first end and a second end wherein the shape memory spring strut is extendable from a first length to a second length and the shape memory spring strut contains a shape memory alloy. This embodiment also includes a shape memory spring strut activation line connected to the shape memory spring strut wherein the shape memory spring strut activation line may be configured to activate the shape memory spring strut and a longitudinal connecting member having a first segment and a second segment wherein the first segment is in pivotal contact with the first end of the shape memory spring strut and the second segment supports a wheel rotatably mounted on a pin. The connecting member may be moveable along a line of travel from an extended position to a retracted position in this embodiment.

RELATED APPLICATIONS

This is a Continuation of U.S. patent application Ser. No. 09/764,117,filed Jan. 19, 2001, now U.S. Pat. No. 6,367,253, which is aContinuation-In-Part of application Ser. No. 09/467,749, filed Dec. 20,1999 and entitled “Heat Converter Engine Using A Shape Memory AlloyActuator,” now U.S. Pat. No. 6,226,992.

FIELD OF THE INVENTION

The present invention relates to mechanical actuators. Moreparticularly, the present invention regards using a shape memory alloyas a power source in mechanical actuators for controlling aircraftlanding gear.

BACKGROUND INFORMATION

A class of materials called shape memory alloys (SMA) exhibits anon-linear relationship between stress and strain when exposed totemperature changes. These alloys undergo a temperature related phasechange that allows the SMA to return to any mechanical configurationimposed on the SMA when it is annealed. When the SMA is below itscritical temperature, it becomes malleable and may be deformed into anyarbitrary shape. Upon heating the SMA above the critical temperature, itundergoes a change in crystal structure and quickly resumes its stifforiginal shape. Cooling the SMA to below the critical temperature will,again, cause it to return it to the cold malleable condition allowing itto be deformed, but always returning to its original shape when it isheated above the critical temperature. The best known SMA is Nitinol, atitanium nickel alloy, having 53.5-56.5% nickel content by weight. Witha temperature change of as little as 18° F., Nitinol can exert a forceof as much as 60,000 psi when exerted against a resistance to changingits shape.

Several prior art patents have disclosed the use of SMAs as actuators.For example, U.S. Pat. No. 4,932,210 to Julien et al. discloses the useof a shape memory alloy actuator for accurately pointing or aligning amoveable object. The SMA elements are arranged in a push-pullconfiguration so that one element in the activated state moves theobject while another element on the opposite side in the soft state actsas a dynamic damper to prevent overtravel of the object. Similarly, U.S.Pat. No. 5,061,914 to Busch et al. discloses SMA actuators that aremechanically coupled to one or more movable elements such that thetemperature induced deformation of the actuators exerts a force orgenerates motion of the mechanical element. However, these systems areused for precision type operations and produce little output power.These systems are not suitable for producing enough power to drive smallpumps or motors, for example, a water pump in an automobile.

Several prior art patents also describe the use of SMAs to drive a shaftin a motor. For example, U.S. Pat. No. 4,665,334 to Jamieson discloses arotary stepping device having a rotatable shaft which is driven by acoiled spring clutch. An actuator made of an SMA is heated and used topull the spring clutch to tighten it and rotate the shaft. When the SMAis cooled it returns to its malleable state and releases the springclutch which loosens from around the shaft and returns to its originalposition without rotating the shaft in the opposite direction. U.S. Pat.No. 4,027,479 to Cory discloses a heat engine with an endless belt whichincludes a number of high density elements secured to lengths of SMAwire. The belt is attached to a pulley connected to a shaft. Twoportions of the belt are maintained at different temperatures and thebelt is constrained to move the elements in a continuous path into afield attracting the elements at the hot portion and out of the field atthe cold portion. The SMA wire in the cold portion is stretched and theSMA wire in the hot portion contracts resulting in higher elementdensity on the portion entering the field and thus a net force drivesthe belt about the pulley. However, these systems are also limited intheir energy output and their complicated construction makes themimpractical for use in standard machinery such as an engine or motor.

SUMMARY OF THE INVENTION

Shape memory alloy actuators for aircraft landing gear are provided. Inone embodiment a retractable aircraft landing gear system is provided.This embodiment includes a shape memory spring strut having a first endand a second end wherein the shape memory spring strut is extendablefrom a first length to a second length and the shape memory spring strutcontains a shape memory alloy. This embodiment also includes a shapememory spring strut activation line connected to the shape memory springstrut wherein the shape memory spring strut activation line may beconfigured to activate the shape memory spring strut and a longitudinalconnecting member having a first segment and a second segment whereinthe first segment is in pivotal contact with the first end of the shapememory spring strut and the second segment supports a wheel rotatablymounted on a pin. The connecting member may be moveable along a line oftravel from an extended position to a retracted position in thisembodiment.

In a second embodiment a method of retracting aircraft landing gear isprovided. This method comprises activating a shape memory alloy within ashape memory spring strut wherein the shape memory alloy is activatedvia a shape memory spring strut activation line in contact with theshape memory spring strut, the shape memory spring strut having a firstend and a second end and being extendable from a first length to asecond length.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a shows a first view of an exemplary shape memory spring (SMS)according to the present invention.

FIG. 1b shows a first view of an exemplary shape memory spring (SMS)according to the present invention.

FIG. 2 shows a first view of an exemplary heat converter engineaccording to the present invention.

FIG. 3 shows a second view of an exemplary heat converter engineaccording to the present invention.

FIG. 4 shows a third view of an exemplary heat converter engineaccording to the present invention.

FIG. 5 shows a top view of an exemplary conveyor belt system for a heatconverter engine according to the present invention.

FIG. 6 shows an exemplary SMS assembly for a heat converter engineaccording to the present invention.

FIG. 7 shows a detail view of an exemplary SMS assembly coupled toexemplary crank shafts in a heat converter engine according to thepresent invention.

FIG. 8 shows an exemplary system for powering a conveyor system in aheat converter engine according to the present invention.

FIG. 9 shows an exemplary system for derailing an SMS assembly coupledto crank shafts in a heat converter engine according to the presentinvention.

FIG. 10 shows a front view of a heat converter engine according to thepresent invention.

FIG. 11 shows an exemplary manner of applying a heating and coolingmedium to a heat converter engine according to the present invention.

FIG. 12 shows an exemplary heat converter engine of the presentinvention as an alternative power source for mechanisms in anautomobile.

FIG. 13 shows an alternative embodiment of a crank shaft for a heatconverter engine according to the present invention.

FIG. 14a shows a time versus speed curve for an exemplary heat converterengine having a substantially circular crank shaft according to thepresent invention.

FIG. 14b shows a time versus speed curve for an exemplary heat converterengine having an alternatively shaped crank shaft according to thepresent invention.

FIG. 15 shows an exemplary link of a flexible crank shaft for a heatconverter engine according to the present invention.

FIG. 16 shows an exemplary manner of coupling an exemplary SMS assemblyto an exemplary link of a flexible crank shaft for a heat converterengine according to the present invention.

FIG. 17 shows an alternative embodiment of a heat converter engineaccording to the present invention.

FIG. 18 shows an alternative embodiment wherein a heat converter engineaccording to the present invention may be used as an electric generator.

FIG. 19 shows an exemplary embodiment of an alternative actuatorassembly for a heat converter engine according to the present invention.

FIG. 20a shows a first view of an exemplary actuator arm of an exemplaryembodiment of an actuator assembly for a heat converter engine accordingto the present invention.

FIG. 20b shows a second view of an exemplary actuator arm of anexemplary embodiment of an actuator assembly for a heat converter engineaccording to the present invention.

FIG. 21a shows a first exemplary embodiment of a hub and spoke assemblyof an actuator assembly for a heat converter engine according to thepresent invention.

FIG. 21b shows a second exemplary embodiment of a hub and spoke assemblyof an actuator assembly for a heat converter engine according to thepresent invention.

FIG. 22a shows a first exemplary embodiment of an actuator arm of anactuator assembly for a heat converter engine according to the presentinvention.

FIG. 22b shows a second exemplary embodiment of an actuator arm of anactuator assembly for a heat converter engine according to the presentinvention.

FIG. 23 shows a detail view of an actuator assembly according to thepresent invention.

FIG. 24 shows an exemplary embodiment of a heat converter engine poweredby an actuator assembly according to the present invention.

FIG. 25 shows a detail view of an exemplary actuator arm from anexemplary embodiment of a heat converter engine powered by an actuatorassembly according to the present invention.

FIG. 26 shows an exemplary embodiment of an actuator assembly and a maincase from an exemplary embodiment of a heat converter engine accordingto the present invention.

FIG. 27 shows an exemplary embodiment of a system for heating a heatingmedium to be used in the present invention.

FIG. 28 shows a second exemplary embodiment of an actuator assemblyaccording to the present invention.

FIG. 29 shows an aircraft landing gear in an extended position inaccordance with an alternative embodiment of the present invention.

FIG. 30 shows an aircraft landing gear in a semi-extended position inaccordance with an alternative embodiment of the present invention.

FIG. 31 shows an aircraft landing gear in a retracted position inaccordance with an alternative embodiment of the present invention.

FIG. 32 shows an airplane landing gear in an extended position inaccordance with an alternative embodiment of the present invention.

FIG. 33 shows an aircraft landing gear in an extended position understatic load in accordance with an alternative embodiment of the presentinvention.

FIG. 34 shows an aircraft landing gear in an extended airborne positionin accordance with an alternative embodiment of the present invention.

FIG. 35 shows an aircraft landing gear in a semi-extended position inaccordance with an alternative embodiment of the present invention.

FIG. 36 shows an aircraft landing gear in a retracted position inaccordance with an alternative embodiment of the present invention.

FIG. 37 shows a motor vehicle wiper arm and identifies the enlarged areaseen in FIGS. 38 and 39.

FIG. 38 shows an enlarged view of one end of a motor vehicle wiper armin a relaxed state in accordance with an alternative embodiment of thepresent invention.

FIG. 39 shows an enlarged view of one end of a motor vehicle wiper armin a compressed state in accordance with an alternative embodiment ofthe present invention.

FIG. 40 shows a motor vehicle wiper arm in accordance with analternative embodiment of the present invention.

FIG. 41 shows a locking assembly in accordance with an alternativeembodiment of the present invention.

FIG. 42 shows a locking assembly in accordance with an alternativeembodiment of the present invention.

FIG. 43 shows a solar array mounted to shape memory alloy supports inaccordance with an alternative embodiment of the present invention.

FIG. 44 shows a solar array mounted to shape memory alloy supports inaccordance with an alternative embodiment of the present invention.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare provided with the same reference numerals. FIGS. 1a-b show a shapememory spring (SMS) 10 constructed of a shape memory alloy (SMA), forexample, Nitinol. As described above, when an SMA is below its criticaltemperature, it becomes malleable and may be deformed into any shape.However, when the SMA is heated above its critical temperature the alloyundergoes a temperature related phase change allowing it to return tothe mechanical configuration imposed on the material when it wasannealed. FIG. 1a shows SMS 10 in its original compressed shape, i.e.,above the SMAs critical temperature. Therefore, when the SMA of SMS 10is heated above its critical temperature, SMS 10 returns to thecompressed state as illustrated in FIG. 1a. FIG. 1b shows SMS 10 whenthe SMA is below its critical temperature. Because the SMA is malleablebelow its critical temperature, SMS 10 may be stretched, increasing itslength. The purpose of this particular deformation will be described ingreater detail below. Those skilled in the art will understand that thisdeformation is only exemplary and that it is also possible to anneal SMS10 so that the stretched state is the original state and SMS 10 may becompressed when the SMA is malleable.

FIG. 2 shows inner crank shaft carrier 20, outer crank shaft carrier 30,inner derail 40 and outer derail 50 according to a first embodiment ofheat converter engine 15 of the present invention. Outer crank shaftcarrier 30 is substantially cylindrical having raised walls 31 and 32which form channel 33 around the circular perimeter of outer crank shaftcarrier 30. Outer derail 50 is integrally connected to outer crank shaftcarrier 30 such that raised wall 31 continues around the outsideperimeter of outer derail 50. Outer derail 50 also has raised wall 51,which, along with raised wall 31 forms channel 53 in outer derail 50.Channel 33 of outer crank shaft carrier 30 and channel 53 of outerderail 50 form a single continuous channel through outer crank shaftcarrier 30 and outer derail 50. The purpose of this continuous channelwill be described in greater detail below. Inner crank shaft carrier 20is substantially similar in shape to outer crank shaft carrier 30,including having channel 23. Inner crank shaft carrier 20 is smaller andfits inside the hollow center of outer crank shaft carrier 30. Innerderail 40 is substantially similar in shape to outer derail 50,including having channel 43. When inner crank shaft carrier 20 is placedinside outer crank shaft carrier 30 the inner derail 40 and outer derail50 should be aligned so that channel 43 is substantially parallel tochannel 53. Those skilled in the art will understand that thearrangement of heat converter engine 15 shown in FIG. 2 is onlyexemplary and that there are other arrangements for the elements shownin this figure. For example, channel 43 of inner derail 40 may bearranged so that it faces inward towards axis 25 of inner crank shaftcarrier 20 and opposes channel 53 of outer derail 50. In thisarrangement, channel 23 may be formed on the inside surface of the outerperimeter of inner crank shaft carrier 20 so that channel 23 and channel43 form a continuous channel.

FIG. 3 shows inner crank shaft 60 located on inner crank shaft carrier20 and outer crank shaft 70 located on outer crank shaft carrier 30added to heat converter engine 15. Inner crank shaft 60 and outer crankshaft 70 are mounted on their respective crank shaft carriers 20 and 30so they may rotate freely. Those skilled in the art will understand thatthere are numerous manners of mounting crank shafts 60 and 70 to crankshaft carriers 20 and 30. FIG. 3 also shows another feature of interestin outer crank shaft carrier 30 and outer derail 50. Slit 34 runs alongthe entire length of channel 33 in outer crank shaft carrier 30 and slit54 runs along the entire length of channel 53 in outer derail 50. Thepurpose of slits 34 and 54 will be described in greater detail below.

FIG. 4 shows additional components added to heat converter engine 15,including SMS 10 (shown in sketch form as bars), outer SMS carriers 90and conveyor belt 100 which is coupled to conveyor belt gears 110 and115. The number of outer SMS carriers 90 shown in FIG. 4 is onlyexemplary and it should be understood that there is an outer SMS carrier90 corresponding to each SMS 10 in heat converter engine 15. Conveyorbelt 100 is driven by conveyor belt gear 110 in the direction of arrow116 and continuously loops around conveyor belt gears 110 and 115. Themechanism to drive conveyor belt gear 110 will be described in greaterdetail below. FIG. 5 shows a top view of conveyor belt 100 which hasflat inner surface 101 that comes in contact with conveyor belt gears110 and 115 and ribbed outer surface 102. Ribs 103 form pockets 104 onribbed outer surface 102. Referring back to FIG. 4, wheels 91 of outerSMS carriers 90 engage in pockets 104 of conveyor 100 as SMS carriersenter outer derail 50, thereby coupling outer SMS carriers 90 toconveyor belt 100. The coupling of outer SMS carriers 90 to conveyorbelt 100 also causes outer SMS carriers 90 to move through channel 53 ofouter derail 50 in the direction of arrow 116. Those skilled in the artwill understand that SMS carriers 90 may be coupled in other manners toconveyor 100 in such a way that the rotation of conveyor 100 is impartedto SMS carriers 90. Those skilled in the art will also understand thatthere is a corresponding conveyor belt and inner SMS carriers (notshown) that move in the same direction through channel 43 of innerderail 40.

FIG. 6 shows a detail view of SMS 10, outer SMS carrier 90 and inner SMScarrier 120. Inner SMS carrier 120 has wheels 121, pin guide 122 andhook 123. Similarly outer SMS carrier 90 has wheels 91, pin guide 92,wedge guide 93 and a hook (not shown). First end 11 of SMS 10 isconnected to hook 123 of inner SMS carrier 120 and second end 12 of SMS10 is connected to a hook (not shown) of outer SMS carrier 90 creatingSMS assembly 130. As described with reference to FIG. 3, outer crankshaft carrier 30 and outer derail 50 may have slits 34 and 54,respectively. The purpose of slits 34 and 54 is that as outer SMScarrier 90 of SMS assembly 130 moves through channels 33 and 53, SMS 10of SMS assembly 130 may project through slits 34 and 54. Similarly,channels 23 and 43 may also have slits for the projection of SMS 10, ifchannels 23 and 43 are arranged to oppose channels 33 and 53. Throughoutthe figures outer and inner SMS carriers 90 and 120 are shown withvarying numbers of wheels. Those skilled in the art will understand thatthe number of wheels is not important and the purpose of the wheels isto allow the carriers to move freely through the channels.

FIG. 7 shows an exemplary manner of coupling SMS assembly 130 to innercrank shaft 60 and outer crank shaft 70. Inner crank shaft 60 has slot61 which engages pin guide 122 of inner SMS carrier 120. Similarly,outer crank shaft 70 has slot 71 which engages pin guide 92 of outer SMScarrier 90. The purpose of wedge guide 93 will be described in greaterdetail below. When inner SMS carrier 120 is engaged with inner crankshaft 60 and outer SMS carrier 90 is engaged with outer crank shaft 70,SMS assembly 130 is coupled to crank shafts 60 and 70. Thus, as crankshafts 60 and 70 rotate about their respective carriers 20 and 30, SMSassembly 130 also rotates. As will be described in greater detail below,the action of the SMS assemblies causes the crank shafts to rotate.Those skilled in the art will understand that there are numerous mannersof coupling SMS assembly 130 to crank shafts 60 and 70 and the abovedescribed manner is only exemplary. It should also be understood thatcrank shafts 60 and 70 may have numerous slots 61 and 71 located aroundthe entire circumference of each crank shaft so that any number of SMSassemblies 130 may be engaged at any particular time. Also, in FIG. 7,pin guide 122 is shown on the top of inner SMS carrier 120, whereas inFIG. 6, pin guide 122 is shown on the bottom of inner SMS carrier 120.As described above, there are numerous possible arrangements for theelements of heat converter engine 15 and whether inner SMS carrier 120is located inside or outside inner crank shaft 60 determines thelocation of guide 122.

FIG. 8 shows a cross-section of heat converter engine 15 showing a sideview of inner crank shaft carrier 20, outer crank shaft carrier 30 andthe derailing area. This figure shows an exemplary arrangement fordriving outer conveyor belt 100 located in outer derail 50 and innerconveyor belt 105 located in inner derail 40. Gear 160 is coupled toinner crank shaft 60 (not shown) in any number of known manners, forexample, a rotor may be attached to inner crank shaft 60 to impartrotational movement to gear 160. The coupling of gear 160 to gear 161imparts the rotation of inner crank shaft 60 to shaft 165 connected togear 161. The rotation of shaft 165 is imparted to conveyor belts 100and 105 through conveyor belt gears 110 and 111 which are coupled toshaft 165. Those skilled in the art will understand that gears 160 and161 may be selected to control the speed that SMS assemblies 130 movethrough the inner and outer derails 40 and 50 relative to the rotationalspeed of inner crank shaft 60. The speed that SMS assemblies 130 movethrough inner and outer derails 40 and 50 may be determined by numerousfactors including the alloy used for the SMS assembly, the cooling rateof the cooling medium, the length of the derail area, etc.

FIG. 9 shows an exemplary manner of derailing SMS assembly 130 frominner crank shaft 60 and outer crank shaft 70. Derailer 170 includesshaft 172 connected to outer derailing wheel 171 and inner derailingwheel 173. In FIG. 9, derailer 170 is shown offset from inner and outercrank shafts 60 and 70 for illustration purposes. In operation, derailer170 is within the boundaries of inner and outer crank shafts 60 and 70so that outer and inner derailing wheels 171 and 173 may engage pinguides 92 and 122 of outer and inner SMS carriers 90 and 120,respectively. The operation of derailer 170 will be described inreference to the derailment of outer SMS carrier 90, however, it shouldbe understood that the operation is similar for the derailment of innerSMS carrier 120. Derailer 170 rotates about vertical axis 174 as theportion of inner and outer crank shafts 60 and 70 coupled to SMSassembly 130 move towards derailer 170. Pin guide 92 of outer SMScarrier 90 comes into contact with outer derailing wheel 171 of derailer170. The rotation of derailer 170 pushes pin guide 92 out of slot 71 ofouter crank shaft 70 causing SMS assembly 130 to become decoupled fromouter crank shaft 70. Those skilled in the art will understand that theshape of outer and inner derailing wheels 171 and 173 and the directionof rotation of derailer 170 is not important. The purpose of derailer170 is to engage outer and inner SMS carriers 90 and 120 and decouplethem from inner and outer crank shafts 60 and 70. Any known mechanicalor electrical means may be used to control the rotation of derailer 170.The conveyor system and derailing operations described above may betimed with the rotation of the inner and outer crank shafts 60 and 70(the heat converter engines RPM).

An exemplary manner of operating heat converter engine 15 will bedescribed in more detail with reference to FIGS. 4 and 10. FIG. 10 showsa front view cross-section of heat converter engine 15 showing SMSassemblies 130 a-g, inner crank shaft 60 and outer crank shaft 70. Therotation of crank shafts 60 and 70 coupled to SMS assemblies 130 a-gwill be described in more detail with reference to an exemplary SMSassembly. The exemplary SMS assembly may be considered to start at theposition of SMS assembly 130 a, where it has been previously heatedabove the critical temperature of the SMA and is in its originalcompressed state. Inner derail 40 and outer derail 50 (not shown) arelocated between the position of SMS assemblies 130 a and 130 b. Thus, asdescribed above, the exemplary SMS assembly may be decoupled or derailedfrom inner crank shaft 60 and outer crank shaft 70 into inner derail 40and outer derail 50 between the positions of SMS assemblies 130 a and130 b. As the exemplary SMS assembly travels through the inner and outerderails 40 and 50, the exemplary SMS assembly is cooled below itscritical temperature and becomes malleable, allowing the SMS to bestretched. The cooled exemplary SMS assembly leaves the inner and outerderails 40 and 50 and re-couples with crank shafts 60 and 70 in theposition of SMS assembly 130 b. As shown in FIG. 10, the exemplary SMSassembly in the position of SMS assembly 130 b has become stretched withrespect to the original length of the SMS shown in the position of SMSassembly 130 a. As crank shafts 60 and 70 continue to rotate in thedirection of arrow 135, the exemplary SMS assembly rotates through thepositions of SMS assemblies 130 c and 130 d where the SMS becomesprogressively longer or more stretched because it remains in itsmalleable state. At a predefined position of the rotation, a heatingmedium will begin to heat the SMS of the exemplary SMS assembly. Thepredetermined position for application of the heating medium may bedetermined by a variety of factors including the alloy used for the SMS,the heat transfer rate of the heating medium, the speed of rotation,etc. As crank shafts 60 and 70 continue to rotate in the direction ofarrow 135, the exemplary SMS assembly is heated above its criticaltemperature and begins to regain its original shape. The beginning ofcompression is when the exemplary SMS assembly is in the position of SMSassembly 130 e. The action of the SMS assembly resuming its originalshape causes a force to be exerted in the radial direction, which, inturn, causes inner crank shaft 60 and outer crank shaft 70 to rotate.Finally, as crank shafts 60 and 70 continue to rotate, the exemplary SMSassembly continues to resume its original shape as it is rotated throughthe positions of SMS assemblies 130 f and 130 g until it fully regainsits original compressed state in the position of SMS assembly 130 a.Thus, rotation of crank shafts 60 and 70 is accomplished by continuousheating and cooling of the SMS assemblies, where the force of the SMSassemblies returning to their original shape causes the crank shafts torotate. Because each of the SMS assemblies 130 a-g are in various statesof compression, inner crank shaft 60 will not be concentric with outercrank shaft 70. However, those skilled in the art will recognize thatinner crank shaft 60, while not centered within outer crank shaft 70,will remain at a fixed position relative to outer crank shaft 70.

Referring back to FIG. 4, a more detailed description of the travel ofthe exemplary SMS assembly through the derail area will be provided. Asdescribed above, the exemplary SMS assembly may be decoupled from theinner and outer crank shafts 60 and 70 by the derailer (not shown) whenthe exemplary SMS assembly has been heated and regained its originalcompressed shape. As the exemplary SMS assembly enters the derail area,outer SMS carrier 90 may be coupled to conveyor belt 100 and inner SMScarrier (not shown) may be coupled to the conveyor belt in inner derail40. Also as described above, the conveyor belts rotate in the directionof arrow 115 and the exemplary SMS assembly rotates through channels 43and 53 when it is coupled to the conveyor belts. A cooling medium isapplied to the exemplary SMS assembly as it travels through the derailarea to cool the SMA alloy below the critical temperature so SMS 10becomes malleable. Those skilled in the art will understand that theexemplary SMS assembly may begin to stretch as it travels through thederail area because the distance between crank shafts 60 and 70 at thelocation where the exemplary SMS assembly is re-coupled to crank shafts60 and 70 is greater than the location where the exemplary SMS assemblyis decoupled from crank shafts 60 and 70. The decoupling of the heatedSMS assemblies from crank shafts 60 and 70 to be cooled in the derailarea eliminates resistance against the SMS assemblies that are beingheated and compressing as described above with reference to FIG. 10. Theelimination of this resistance results in a more powerful and efficientheat convertor engine.

FIG. 11 shows the relative positions of the application of the heatingand cooling mediums to heat converter engine 15. As described above,cooling medium 140 may be applied to the SMS assemblies (not shown) whenthey are located in the area of inner derail 40 and outer derail 50.Similarly, heating medium 150 may be applied to the SMS assemblies at apredetermined position when the SMS assemblies are coupled to crankshafts 60 and 70. Those skilled in the art will understand that any gasor liquid may be used to heat or cool the SMS assemblies, for example,air, water or a refrigerant may be used. Likewise, the heating orcooling medium may be contained in either an open system, where theheating or cooling medium is exhausted directly into the atmosphere, orin a closed system, where the heating or cooling medium may be recycledthrough the system. Also, the transfer of heat between the mediums andthe SMS assemblies maybe direct or indirect, for example, through a heatexchanger.

FIG. 12 shows an exemplary use of a heat converter engine of the presentinvention as an alternative power source for mechanisms in anautomobile. The use of a heat converter engine in on automobile may beadvantageous because a heating medium (heated exhaust gas) and a coolingmedium (air flow from the fan) are readily available. For example, innercrank shaft 60 may be coupled to drive shaft 65 which, in turn, iscoupled to shaft 181 of transmission 180. Rotor 182 of transmission 180may be coupled to pulley mechanism 200 which is connected to a series ofdrive belts 201-203. First drive belt 201 may be coupled to alternator210, second drive belt 202 may be coupled to power steering pump 220,and third drive belt 203 may be coupled to air conditioning unit 230. Asdescribed above with reference to FIGS. 4 and 10, by heating and coolingSMS assemblies 130 of heat converter engine 15, it is possible to causedrive shaft 65, shaft space 181 and rotor 182 to rotate. The rotation ofrotor 182 may cause pulley 200 to rotate and this rotation may beimparted to each of alternator 210, power steering pump 220 and airconditioning unit 230 by drive belts 201-203, respectively. Thus, theheat converter engine may be used as an alternative power source forthese devices, resulting in lowering the load on the internal combustionengine of the automobile and causing an increase in efficiency. Otherexamples of devices in an automobile that may be powered by thisalternative power source may be water pumps, fuel pumps, etc. Thoseskilled in the art will understand that the pulley and drive belt systemdescribed is only exemplary, and that depending upon the application, adifferential or other similar gearing may be used to impart the correctamount of power to the device using the alternative power source.Additionally, this alternative power source is not limited to automobileor motor vehicle applications, it may be used in any situation where adevice may be powered by imparting mechanical rotation to the enddevice, or it may be used to power a generator which may produceelectrical power for any consumption device. Other examples ofsituations where heating and cooling mediums exist are natural hotsprings or power plants where cooling water is used to cool the plantscomponents.

FIG. 13 shows an alternative embodiment for outer crank shaft carrier240 and outer crank shaft 250. In this embodiment, outer crank shaftcarrier 240 has a substantially straight section 241 connected to anarc-shaped section 242, and outer crank shaft 250 is flexible to rotateabout outer crank shaft carrier 240. Note that the derail portion of theheat converter engine is not shown in FIG. 13. FIG. 17 shows an exampleof a heat converter engine including outer crank shaft carrier 240 andthe derail area. A plurality of links 260 are coupled to form flexibleouter crank shaft 250. The remaining elements and operation of a heatconverter engine having outer crank shaft carrier 240 and flexible outercrank shaft 250 are the same as those described above. The shape ofouter crank shaft carrier 240 allows the flexible outer crank shaft 250to rotate faster and have a more constant RPM. For example, FIG. 14ashows a time versus speed curve for a heat converter engine having asubstantially circular outer crank shaft carrier and outer crank shaftas described with reference to FIG. 3. Whereas, FIG. 14b shows a timeversus speed curve for a heat converter engine having the shape of outercrank shaft carrier 240 and flexible outer crank shaft 250. As shown bythese curves, a heat converter engine with the outer crank shaft carriershaped in the form of outer crank shaft carrier 240 produces higherspeeds in a shorter amount of time and provides a more linear timeversus speed characteristic. Those skilled in the art will understandthat each of these designs may be more efficient for any number ofapplications and the particular type of crank shaft will be determinedby the application.

FIG. 15 shows a detail view of exemplary links 260 of flexible outercrank shaft 250. Each link 260 has first end 261, second end 262 andmiddle section 263. First end 261 has a substantially cylindricalsection 264 which has hollow center 267. Two arc-shaped surfaces 265 and266 formed in middle section 263 are adjacent to cylindrical section 264and have substantially the same curvature as cylindrical section 264.Second end 262 has two substantially cylindrical sections 268 and 269which have hollow centers 268 and 269, respectively. Arc-shaped surface273 formed in middle section 263 is between cylindrical sections 271 and272 and has substantially the same curvature as cylindrical sections 271and 272. Slot 275 is formed in middle section 263 and will be describedin greater detail below. Links 260 may be coupled by insertingcylindrical section 264 of first end 261 into arc shaped surface 273 ofsecond end 262. This insertion also causes cylindrical sections 268 and269 of second end 262 to be inserted in arc shaped surfaces 265 and 266of first end 261. The result of this insertion is that hollow centers267, 271 and 272 of cylindrical sections 264, 268 and 269, respectively,form a continuous via through links 260 with a substantially uniformdiameter. Connection pin 680 may be inserted into the via to couplelinks 260. A plurality of links 260 may be coupled to form flexibleouter crank shaft 250.

FIG. 16 shows a detail view of exemplary link 260 coupled to outer SMScarrier 90. Link 260 has slot 275 which is a cut out having twosubstantially straight sections connected by an arc shaped sectionrunning from the top to the bottom of link 260. At a predetermineddistance from the top, the diameter of slot 275 is narrowed causing aridge 276 to be formed in slot 275. Ridge 276 is closer to the top atthe edge of slot 275 and tapers to be farther away from the top as itnears the arc section of slot 275. Outer SMS carrier 90 has pin guide 92and wedge guide 93. Wedge guide 93 has substantially the same shape asslot 275 and is also tapered to widen in the arc section. As SMS carrier90 is engaged in link 260, wedge guide 93 is seated on ridge 276 of slot275 until the bottom of the arc section of wedge guide 93 comes intocontact with the arc section of slot 275, coupling SMS carrier 90 tolink 260. In this manner, SMS assemblies may be coupled to the outercrank shaft in heat converter engines having the shape described forouter crank shaft carrier 240 with reference to FIG. 13.

FIG. 17 shows an exemplary embodiment of a heat converter engine thathas storage areas 300 and 310 for broken SMS assemblies and replacementSMS assemblies. The features of the exemplary heat converter engine arethe same as described above, except that inner and outer derails 40 and50 have additional storage areas 300 and 310. (Storage area 310 of innerderail 40 is not shown). Storage areas 300 and 310 form additionalchannels through which SMS assemblies may be moved. Sensor 290 senseswhether an SMS assembly is in disrepair, for example, a broken SMS orcarrier. Those skilled in the art will understand that there arenumerous types of sensors that may be configured to detect a broken SMSor carrier, for example, a load sensor such as a spring loaded switch ora light beam sensor. When sensor 290 determines that an SMS assembly isin disrepair, it may send a signal to a derailer to derail the brokenSMS assembly from-outer and inner derail 40 and 50 into storage area 300in the direction of arrow 301. Those skilled in the art will understandthat a derailer similar to the one described above may be used for thispurpose. New SMS assemblies may be stored in storage area 310, and whena broken SMS assembly is removed from outer and inner derail 40 and 50,a new SMS assembly from storage area 310 may move into the positionvoided by the broken spring. The new SMS assembly may move into outerand inner derail 40 and 50 in the direction of arrows 311. Those skilledin the art will understand that there are numerous methods ofcontrolling the timing of moving the new SMS assembly into the positionvoided by the broken SMS assembly.

FIG. 18 shows an exemplary arrangement wherein a heat converter enginemay operate as a generator or alternator. SMS assembly 130 is shownhaving SMS 10, outer SMS carrier 90 and inner SMS carrier 120. Outer SMScarrier 90 has wheels 96 and 97 which are constructed of a magneticmaterial, where wheel 96 has the opposite polarity of wheel 97.Similarly, inner SMS carrier 120 has wheels 126 and 127 constructed of amagnetic material, where wheel 126 has the opposite polarity of wheel127. Inner crank shaft carrier 20 has coil 26 and outer crank shaftcarrier 30 has coil 36. SMS assembly 130 travels through inner crankshaft carrier 20 and outer crank shaft carrier 30 which are bothstationary. As the magnetic wheels of the outer and inner SMS carriers90 and 120 pass through coils 26 and 36 of inner and outer crank shaftcarriers 20 and 30, the movement induces a current to flow in coils 26and 36. Thus, a heat converter engine rather than powering anautomobiles alternator as described with respect to FIG. 12 may alsoserve as the alternator for an automobile.

Alternative Embodiments

FIG. 19 shows an actuator assembly 401 according to a first alternativeembodiment of the present invention, which includes a hub and spokeassembly 402 having hub 403 and circular spokes 404-409, and actuatorarms 414-419. At least a portion of actuator arms 414-419 of actuatorassembly 401 are constructed of a shape memory alloy (SMA), for example,Nitinol. Hub and spoke assembly 402 of actuator assembly 401 may beconsidered a crank shaft and may be constructed from any suitablematerial that is not an SMA, for example, metal, plastic, or rubber.Actuator assembly 401 may rotate about axis 420 of hub 403 in eitherdirection as shown by arrow 421. The purpose of rotating actuatorassembly 401 will be described in greater detail below. Those skilled inthe art will understand that the number of spokes and actuator armsshown in FIG. 19 are only exemplary and that there may be any number ofspokes and actuator arms based on the particular application intendedfor the actuator assembly.

FIGS. 20a-b show two different views of an exemplary actuator arm ofactuator assembly 401 from FIG. 19, for example, actuator arm 414 whichis constructed of an SMA. As described above, when an SMA is below itscritical temperature, it becomes malleable and may be deformed into anyshape. However, when the SMA is heated above its critical temperaturethe alloy undergoes a temperature related phase change allowing it toreturn to the mechanical configuration imposed on the material when itwas annealed. FIG. 20a shows exemplary actuator arm 414 in its originalshape, i.e., above the SMAs critical temperature. In FIG. 20a, exemplaryactuator arm 414 has a first end 430 connected to second end 431 by asubstantially straight middle section 432. Therefore, when the SMA ofexemplary actuator arm 414 is heated above its critical temperature,actuator arm 414 returns to the shape illustrated in FIG. 20a. FIG. 20bshows exemplary actuator arm 414 when the SMA is below its criticaltemperature. Because the SMA is malleable below its criticaltemperature, actuator arm 414 may deform into some other shape. Forexample, in FIG. 20b, middle section 432 is shown as deformed into acurved shape. Those skilled in the art will understand that thisdeformation is only exemplary and that when the SMA is malleable anyportion of actuator arm 414 may be deformed depending on the forcesacting upon actuator arm 414. The purpose of this particular deformationwill be described in greater detail below. Additionally, as shown inFIGS. 20a and 20 b, the entire exemplary actuator arm 414 is constructedof an SMA. Depending on the particular purpose and use of the actuatorarm, it may be possible to construct only a portion of actuator arm 414of SMA. For example, if the only deformation required of actuator arm414 is that shown in FIG. 20b, it may be possible to only constructmiddle section 432 of an SMA and first end 430 and second end 431 ofsome other material.

FIG. 21a shows a first exemplary embodiment of hub and spoke assembly402 of actuator assembly 401 from FIG. 19. FIG. 21a shows a sectionalview of hub 403 and spokes 404, 405 and 409. The features of the spokeswill be described with respect to spoke 409, but these features aretypical for all the spokes. Spoke 404 has a generally cylindrical shapewith a solid first end and an open second end which is an intake port441 leading to hollow inside cavity 450. Wall 445 of spoke 404 ispreferably formed as a generally cylindrical surface except for afeature of interest in the present invention. Exhaust port 442 in wall445 provides a via from hollow cavity 450 to outside of spoke 404.Intake port 441 and exhaust port 442 may be used to conduct the flow ofgas or fluid heating and/or cooling mediums to the actuator arms. Intakeport 441 has a generally circular shape and exhaust port 442 has agenerally rectangular shape. However, the shape of intake port 441 andexhaust port 442 is not critical, as there may be different optimumshapes for various heating and cooling mediums. As will be described ingreater detail below, an intake port of an actuator arm may bepositioned adjacent to exhaust port 442 so the flow of the heating orcooling medium may enter the actuator arm as it leaves spoke 404. Forexample, hot air may flow into spoke 409 through intake port 441 in thedirection of arrow 451 into hollow inside cavity 450 and out exhaustport 442 in the direction of arrow 452. Those skilled in the art willunderstand that any gas or liquid may be used to heat or cool theactuator arms. For example, in addition to air, water or a refrigerantmay be used.

FIG. 22a shows a first exemplary embodiment of an exemplary actuator armof actuator assembly 401 from FIG. 19, for example, actuator arm 414.This embodiment of actuator arm 414 may be used in conjunction with theexemplary hub and spoke assembly 402 described with reference to FIG.21a. As described above, actuator arm 414 is constructed of an SMA andhas a first end 430 connected to a second end 431 by middle section 432.First end 430 has intake port 460 which has the same general shape asexhaust port 442 of spoke 404 described with reference to FIG. 21a. Whenactuator arm 414 is positioned in conjunction with hub and spokeassembly 402, intake port 460 is adjacent to exhaust port 442 of spoke404. Actuator arm 414 has hollow channel 461 leading from intake port460 through the entire length of middle section 432 to exhaust port 462in second end 431. Intake port 460, hollow channel 461 and exhaust port462 allow the heating or cooling medium from hub and spoke assembly 402to flow through the entire inside length of actuator arm 414 so that theSMA of actuator arm 414 is uniformly heated or cooled. For example, thehot air flow described above, may leave spoke 409 through exhaust port442 and enter actuator arm 414 through intake port 460 in the directionof arrow 465, flow through hollow channel 461 heating the SMA to abovethe critical temperature, causing actuator arm 414 to return to itsoriginal shape. The hot air may continue to flow through exhaust port462 in the direction of arrow 466 to exit actuator arm 414. Similarly,any cooling medium may also be used to cool actuator arm 414 to belowits critical temperature so that it becomes malleable. Those skilled inthe art will understand that the heating or cooling medium may becontained in either an open system, where the heating or cooling mediumis exhausted directly into the atmosphere, or in a closed system, wherethe heating or cooling medium may be recycled through the system.

FIG. 21b shows a second exemplary embodiment of hub and spoke assembly402 of actuator assembly 401 from FIG. 19. FIG. 21b shows a sectionalview of hub 403 and spokes 404, 405 and 409. The features of the spokeswill be described with respect to spoke 404, but these features aretypical for all the spokes. Spoke 404 has a generally cylindrical shapewith intake port 471 in a first end which leads to first hollow cavity473 and exhaust port 472 in a second end which leads to a second hollowcavity 474. First hollow cavity 473 is separated from second hollowcavity 474 by a solid wall (not shown) that prevents any direct flow ofheating or cooling medium between these cavities. Wall 475 of spoke 404is preferably formed as a generally cylindrical surface except for twofeatures of interest in the present invention. First intermediate port476 provides a via from first hollow cavity 473 to outside of spoke 404and second intermediate port 477 provides a via from second hollowcavity 474 to outside of spoke 404. Intake port 471, first intermediateport 476, second intermediate 477 and exhaust port 472 may be used toconduct the flow of a heating or cooling medium to and from the actuatorarms of the actuator assembly. As described above, the shape of ports471, 472, 476 and 477 is not critical, as there may be different optimumshapes depending on the particular heating or cooling medium. As will bedescribed in greater detail below, two ports of an actuator arm may bepositioned adjacent to first intermediate port 476 and secondintermediate port 477 so that the flow of the heating or cooling mediummay enter and exit the actuator arm. For example, hot air may flow intospoke 409 through intake port 471 in the direction of arrow 481 intofirst hollow cavity 473 and then out first intermediate port 476 in thedirection of arrow 482. When the flow leaves first intermediate port 476it enters a port of an actuator arm that is adjacent to firstintermediate port 476. The flow of the heating or cooling medium throughthe actuator arm will be described in greater detail below. The flowleaves the actuator arm through a port that is positioned adjacent tosecond intermediate port 477. The flow leaving the actuator arm willenter second intermediate port 477 in the direction of arrow 483 intosecond hollow cavity 474 and out of spoke 404 through exhaust port 472in the direction of arrow 484.

FIG. 22b shows a second exemplary embodiment of an exemplary actuatorarm of actuator assembly 401 from FIG. 19, for example, actuator arm414. This embodiment of actuator arm 414 may be used in conjunction withthe exemplary hub and spoke assembly 402 described with reference toFIG. 21b. As described above, actuator arm 414 is constructed of an SMAand has first end 430 connected to second end 431 by middle section 432.First end 430 has intake port 490 which has the same general shape asfirst intermediate port 476 of spoke 404, as described with reference toFIG. 4b. First end 430 also has exhaust port 491 which has the samegeneral shape as second intermediate port 477 of spoke 404, as describedwith reference to FIG. 21b. When actuator arm 414 is positioned inconjunction with hub and spoke assembly 402, intake port 490 is adjacentto first intermediate port 476 of spoke 404 and exhaust port 491 isadjacent to second intermediate port 477. Actuator arm 414 has a hollowchannel 493 which has a first section 501 running from intake port 490through middle section 432 towards second end 431. Prior to enteringsecond end 431, hollow channel 493 has a second section 502 that is atsubstantially a right angle to first section 501. A third section 503 ofhollow channel 493 is at substantially a right angle to second section502 and runs to exhaust port 491. Those skilled in the art willunderstand that the shape of hollow channel 493 is not important, theimportance of hollow channel 493 is that it delivers the flow of theheating or cooling medium to the SMA portion of actuator arm 414 so thatit may be uniformly heated or cooled. For example, the hot air flowdescribed above with reference to FIG. 21b, may leave spoke 409 throughfirst intermediate port 476 and enter actuator arm 414 through intakeport 490 in the direction of arrow 506, flow through channel 493 heatingthe SMA to above its critical temperature and causing actuator arm 404to return to its original shape. The hot air may continue to flowthrough exhaust port 491 in the direction of arrow 407, exiting actuatorarm 414 and reentering spoke 409 through second intermediate port 477.

FIG. 23 shows an exemplary manner of attaching the actuator arms to thehub and spoke assembly. In this embodiment, first end 430 of exemplaryactuator arm 419 is constructed in a circular shape so that the firstend 430 fits into circular cavity 510 formed by spokes 404 and 409. Thisconstruction assures that actuator arms 414-419 are not separated fromhub and spoke assembly 402 in the radial direction as actuator assembly401 rotates about axis 420 of hub 403, as described with reference toFIG. 19. As will be described in greater detail below, actuator assembly401 may be inserted into a case to prevent actuator arms 414-419 fromseparating from hub and spoke assembly 402 in the axial direction. Thisconstruction allows for easy insertion and removal of actuator arms bymoving first end 430 in the axial direction into and out of cavity 510.In this embodiment, exhaust port 442 of spoke 404 is adjacent to intakeport 460 of actuator arm 419, as described with reference to FIGS. 21aand 22 a, respectively. Similarly, this embodiment allows firstintermediate port 476 of spoke 404 to be adjacent to intake port 490 ofactuator arm 419 and second intermediate port 477 of spoke 404 to beadjacent to exhaust port 491 of actuator arm 419, as described withreference to FIGS. 21b and 22 b. Those skilled in the art willunderstand that there are many possible manners of connecting theactuator arms to the hub and spoke assembly, for example, through theuse of other integrally formed shapes or by using mechanical fasteners.In addition, it is possible to form the hub in such a manner that theactuator arms may be connected directly to the hub such that spokes arenot necessary.

FIG. 24 shows an exemplary embodiment of heat converter engine 600powered by an exemplary actuator assembly of the present invention. Heatconverter engine 600 includes actuator assembly 610 which is positionedinside main case 620. First end 631 of drive shaft 630 is insertedthrough opening 611 in actuator assembly 610 and opening 622 in maincase 620. Drive shaft 630 is coupled with shaft 641 of transmission 640through first sealed bearing 650. Second sealed bearing 651 is coupledto second end 632 of drive shaft 630 so that drive shaft 630 may rotatefreely. Insertion of drive shaft 630 through opening 611 in actuatorassembly 610 rigidly couples drive shaft 630 to actuator assembly 610 sothat as actuator assembly 610 rotates inside main case 620, thisrotation is imparted to drive shaft 630. Coupling of drive shaft 630 andactuator assembly 610 may be accomplished by any conventional means. Theaction that drives the rotation of actuator assembly 610 will bedescribed in greater detail below. Actuator assembly 610 is sealedwithin main case 620 by cover 660. As described above, cover 660prevents the actuator arms of actuator assembly 610, for exampleactuator arm 614, from separating from hub and spoke assembly 613 in theaxial direction. A heating medium intake 670 and a cooling medium intake680 are connected to cover 660 which has two vias (not shown) to allowthe heating and cooling mediums to enter the area of main case 620 whenengine 600 is sealed.

FIG. 25 shows a detail view of exemplary actuator arm 616 of actuatorassembly 610 from FIG. 24. This sectional view shows second end 431 ofactuator arm 616 that comes in contact with inside cylindrical wall 621of main case 620 as shown in FIG. 24. Second end 431 of actuator arm 616has two sealed bearings 655 and 656. As actuator assembly 610 rotateswithin main case 620, sealed bearings 655 and 656 come in contact withinside wall 621 and allow actuator assembly 610 to rotate freely withinmain case 620. Those skilled in the art will understand that this isonly an exemplary embodiment of the portion of the actuator assemblythat comes in contact with the main case and that there are numerousmanners of constructing the actuator assembly or the main case such thatthe actuator assembly will rotate freely while in contact with theinside wall of the main case.

Referring back to FIG. 24, an exemplary manner of causing actuatorassembly 610 to rotate within main case 620 is the following: A coolingmedium is input through cooling medium intake 680. The via in cover 660which allows the cooling medium to enter the area of main case 620 ispositioned so that the cooling medium will enter an intake port of huband spoke assembly 613 of actuator assembly 610, for example, intakeport 441 as described with reference to FIG. 21a. The cooling mediumwill then flow through hub and spoke assembly 613 and into actuator arms614-619, cooling actuator arms 614-619 below the critical temperature ofthe SMA, causing actuator arms 614-219 to become malleable and able tobe deformed from their original shape. As actuator assembly 610 rotatesinside main case 620, only one intake port of a spoke will be positionedadjacent to the via at each instant of time. Thus, cooling medium intake680, the via and the intake port of the spoke should be sized so thatduring the single pass in each rotation, enough cooling medium may flowinto the actuator arm to cool it below its critical temperature.However, those skilled in the art will understand that it may bepossible to design an actuator assembly where each actuator arm does notneed to be cooled to below its critical temperature during each rotationof the actuator assembly.

In this embodiment, the original shape of actuator arms 614-619 issubstantially straight as shown in FIG. 24. When the actuator arms aremalleable, the force exerted on the arms by coming in contact withinside wall 621 of main case 620 will cause a curvature to be formed inactuator arms 614-619, as described with reference to FIG. 20b. Thoseskilled in the art will understand that, in operation, all of actuatorarms 614-619 of actuator assembly 610 will not simultaneously be intheir original shape as shown in FIG. 24. Some of the arms may be cooledto below the critical temperature of the SMA and have the curved shapedescribed above. In this embodiment, opening 611 of actuator assembly610 will not be centered with respect to main case 620. For example,with reference to FIG. 26, actuator assembly 610 is shown inserted intomain case 620. As shown, actuator arms 617 and 618 are in their originalsubstantially straight shape, actuator arms 616 and 619 have a slightcurvature from the force exerted on these arms from inside wall 621 ofmain case 620, and actuator arms 614 and 615 have the greatestcurvature. Thus, opening 611 in hub and spoke assembly 613 of actuatorassembly 610 is not centered in main case 620 because of the varyingdegrees of curvature on actuator arms 614-619. However, those skilled inthe art will recognize that opening 611, while not centered within maincase 620, will remain at a fixed position while actuator assembly 610rotates. For example, as actuator assembly 610 rotates, actuator arms617 and 618 that are shown in their original substantially straightshape will be cooled to below their critical temperature and the forceexerted by inside wall 621 of main case 620 will cause these actuatorarms to become curved. At the same time, actuator arms 614 and 615 thatare in the fully curved shape will be heated above the criticaltemperature causing these actuator arms to return to their originalsubstantially straight shape. When this occurs the position of actuatorarms 614 and 615 will essentially be interchanged with the position ofactuator arms 617 and 618, respectively. Thus, actuator assembly 610will have rotated one half rotation, but the axis of rotation aboutopening 611 will not change. To account for this offset of the axis ofrotation from the center of main case 620, opening 622 of main case 620may be offset from center to be in line with opening 611 of actuatorassembly 610.

Again referring back to FIG. 24, when the cooling medium is exhaustedfrom the actuator arm, it flows out of main case 620 through exhaustport 623. Hub and spoke assembly 613 and actuator arms 614-619 may besimilar to those described with reference to FIGS. 21a and 22 a, wherethe heating or cooling medium is exhausted from the actuator assemblythrough an exhaust port on the actuator arm. For example, exhaust port62 of actuator arm 414 in FIG. 22a. Those skilled in the art willunderstand that hub and spoke assembly 613 and actuator arms 614-619 mayalso be similar to those described with reference to FIGS. 21b and 22 b,where the heating or cooling medium is exhausted from the hub and spokeassembly rather than the actuator arm. For example, exhaust port 472 ofthe hub and spoke assembly in FIG. 21b. In this case, exhaust ports 623and 624 of main case 620 may be placed in a different position toaccommodate the exhaust of the heating or cooling medium.

Similar to the intake of the cooling medium, a heating medium is inputthrough heating medium intake 670. The via in cover 660 which allows theheating medium to enter the area of main case 620 is also positioned sothat the heating medium will enter an intake port of the hub and spokeassembly 613 of actuator assembly 610, for example, intake port 441 asdescribed with reference to FIG. 21a. The heating medium will then flowthrough hub and spoke assembly 613 and into actuator arms 614-619,heating the actuator arms above the critical temperature of the SMA andcausing the actuator arms to resume their original shape. As theactuator arms return to their original substantially straight shape, theforce exerted by the actuator arms in the radial direction againstinside wall 621 of main case 620 will cause the entire actuator assemblyto rotate. Concurrently, the rigidity of the actuator arms that areabove the critical temperature will cause the actuator arms that arebelow the critical temperature to be deformed into the curved shape bybeing forced against inside wall 621 of main case 620. The completeaction of rotation will be described in more detail below. Also, asdescribed above, the heating medium may be exhausted from main case 620through exhaust port 624.

Referring back to FIG. 26, the rotation of actuator assembly 610 withinmain case 620 will be described in more detail with reference to anexemplary actuator arm. The exemplary actuator arm may be considered tostart at the position of actuator arm 617, where it has been previouslyheated above the critical temperature of the SMA and is in its originalsubstantially straight shape. As actuator assembly 610 rotates in thedirection of arrow 625, the intake port of the spoke that distributesthe heating and cooling medium to the exemplary actuator arm, forexample, intake port 691 of spoke 697 for actuator arm 617, aligns withthe via allowing the cooling medium to flow into the spoke. The spokedistributes the cooling medium flow to the exemplary actuator arm, forexample, in the manners described above with reference to FIGS. 21a-band 22 a-b. As described above, the via and intake port should be sizedso that a sufficient amount of cooling medium flows into the spoke whilethe via and intake port are aligned to cool the exemplary actuator armbelow its critical temperature. As actuator assembly 610 continues torotate in the direction of arrow 625, the exemplary actuator arm rotatesinto the position of actuator arm 618. In this position, the coolingmedium is cooling the actuator arm, but it is not yet below the criticaltemperature, therefore, the exemplary actuator arm remains in itssubstantially straight original shape. When the exemplary actuator armis in the position of actuator arms 617 and 618, it is rigid and exertsforce in the radial direction against inside wall 621 of main case 620.Concurrently, this rigidity forces actuator arms opposite those in thepositions of actuator arms 617 and 618, for example, actuator arms 614and 615 to be deformed into a curved shape to account for the rigidity.As actuator assembly 610 continues to rotate in the direction of arrow625, the exemplary actuator arm moves into the position of actuator arm619. Between the positions of actuator arm 618 and 619, the coolingmedium has cooled the exemplary actuator arm to below the criticaltemperature so that, when the exemplary actuator arm reaches theposition of actuator arm 619 it is beginning to be deformed into thecurved shape. Actuator assembly 610 continues to rotate in the directionof arrow 625 and the exemplary actuator arm rotates into the position ofactuator arm 614, where the force exerted by a rigid actuator arm in theposition of actuator arm 617 through hub and spoke assembly 613 causesthe exemplary actuator arm to be deformed into the greatest curvature.

Continued rotation of actuator assembly 610 in the direction of arrow625 causes the intake port of the spoke that distributes the heating andcooling medium to the exemplary actuator arm, for example intake port692 of spoke 694 for actuator arm 614, to align with the via allowingthe heating medium to flow into the spoke and then be distributed to theexemplary actuator arm. Again, the via and the intake port should besized so that a sufficient amount of heating medium enters the spokewhile the intake port and via are aligned to heat the exemplary actuatorarm above the critical temperature. As actuator assembly 610 continuesto rotate in the direction of arrow 625, the exemplary actuator armrotates into the position of actuator arm 615 where the heating mediumhas not yet heated the exemplary actuator arm above the criticaltemperature. The exemplary actuator arm remains in the position ofgreatest curvature because of the force exerted by a rigid actuator armin the position of actuator arm 618. Continued rotation of actuatorassembly 610 causes the exemplary actuator arm to move between theposition of actuator arms 615 and 616, where the heating medium hasheated the exemplary actuator arm above the critical temperature so thatthe exemplary actuator arm begins to return to its original shape. Theaction of the actuator arm resuming it original shape causes a force tobe exerted in the radial direction against inside wall 621 of main case620, which, in turn, causes actuator assembly 610 to rotate. Finally, asactuator assembly 610 continues to rotate, the exemplary actuator armresumes its original shape when it reaches the position of actuator arm617.

Thus, rotation of actuator assembly 610 is accomplished by continuousheating and cooling of actuator arms 614-619, where the force of theactuator arms returning to their original shape causes the entireassembly to rotate. Those skilled in the art will understand that theoriginal and deformed shapes described above, i.e., straight and curved,are only exemplary and that other shapes may also be used for theactuator arms to accomplish the same action of causing the actuatorassembly to rotate. Referring back to FIG. 24, the rotation of actuatorassembly 610 also causes drive shaft 630 to rotate which, in turn,causes shaft 641 of transmission 640 to rotate. Through internal gearingin transmission 640, the rotation of shaft 641 is imparted to rotor 642of transmission 640. The rotation of rotor 642 may be used to drive orpower any number of mechanisms.

FIG. 27 shows an exemplary embodiment of a system for heating anddelivering a heating medium to the intake of the heat converter engine.FIG. 27 shows exhaust manifold 700 having intake ports 701-704, mainheader 705 and exhaust port 706. Hot exhaust air from the cylinders ofan internal combustion engine enters intake ports 701-704 in thedirection of arrows 711-714, flows through main header 705 in thedirection of arrow 715 and out exhaust port 706 in the direction ofarrow 716. In addition to exhaust manifold 700, this exemplaryembodiment also has medium delivery system 720, having an intake port721, pump 722, heating coil 723 and exhaust port 724. A liquid heatingmedium enters medium delivery system 720 through intake port 721 and ispumped in the direction of arrow 731 by pump 722. The heating mediumentering medium delivery system 720 is cool, or at least not heated toits ideal temperature. As shown in FIG. 27, at point 735, mediumdelivery system 720 enters the boundary of exhaust manifold 700 in thearea of main header 705. In this area, medium delivery system 720 hasheating coil 723. As the heating medium flows through heating coil 723,the flow of hot exhaust air in header 705 heats the heating medium inheating coil 723 to its ideal temperature. Medium delivery system 720then exits the boundary of exhaust manifold 700 at point 736 and theheated heating medium flows in the direction of arrow 734 out exhaustport 724 of medium delivery system 720. The heating medium may then bedelivered to the heating medium intake of the heat converter engine, forexample heating medium intake 670 of FIG. 24.

Medium delivery system 720 may also be adapted for use by a gaseousheating medium by simply using a fan in place of pump 722 to cause gasflow through the system. Alternatively, it may also be possible to usethe hot exhaust flow from exhaust manifold 700 as a direct input to theheating medium intake of the heat converter engine, thereby eliminatingmedium delivery system 700. Similarly, it may also be possible to have amedium delivery system for delivering the cooling medium to the coolingmedium intake of the heat converter engine, for example cooling mediumintake 680 of FIG. 24. For example, the flow of cooling medium may becooled by a compressor/condenser unit prior to entering the coolingmedium intake. An interesting feature of the cooling medium deliverysystem may be that the compressor/condenser unit may be powered by theheat converter engine, after initial start-up, thereby allowing theentire system to be self-contained.

FIG. 28 shows a first alternative embodiment of an SMA actuator assemblyof the present invention. Actuator assembly 800 has hub and spokeassembly 501 and actuator arms 802-805 and is positioned within maincase 810. Each of actuator arms 802-805 is constructed of an SMA and hasa first end 821 for coupling with hub and spoke assembly 801 and asecond end 822 having sealed bearing 823 that comes in contact with theinside wall 811 of main case 810, allowing actuator assembly 800 tofreely rotate within main case 810. Actuator assembly 800 operates inthe same manner as the previously described actuator assembly in thatthe rotation of actuator assembly 800 within main case 810 is caused bycontinuous heating and cooling of actuator arms 802-805. When actuatorarms 802-805 are cooled they become malleable and are deformed into thecurved shape as shown by actuator arms 802-804, with actuator arm 803having the greatest degree of curvature. As actuator arms 802-805 areheated, they resume their original substantially straight shape, asshown by actuator arm 805. As described above, this action of actuatorarms 802-805 resuming their original shape causes a force to be exertedin the radial direction causing actuator assembly 800 to rotate withinmain case 810.

In this embodiment, actuator arms 805—805 are heated and cooled bydirect application of the heating and cooling mediums to the exterior ofactuator arms 802-805. Main case 810 has a hot gas port 812 and a coldgas port 813 which effect the operation of actuator assembly 800 asfollows: An actuator arm in the position of actuator arm 805 has beenheated and is in its original substantially straight shape. As actuatorassembly 800 rotates in the direction of arrow 830, the actuator armcrosses the boundary 814 of cold gas port 813 and an incoming stream ofcold gas flows over the actuator arm cooling it below the criticaltemperature of the SMA. By the time the actuator arm is cooled below thecritical temperature, it has rotated into the position of actuator arm802 and has started to deform into the curved shape. As actuatorassembly 800 continues to rotate in the direction of arrow 830 theactuator arm is further deformed into a more pronounced curvature thatcoincides with boundary 815 of cold gas port 813. Actuator assembly 800continues to rotate in the direction of arrow 830 and the actuator armcrosses boundary 816 of hot gas port 812 into the position as shown byactuator arm 803. In this position, an incoming stream of hot gas flowsover the actuator arm heating it above the critical temperature of theSMA. By the time actuator assembly 800 has rotated in the direction ofarrow 830 so that the actuator arm has reached the position as shown byactuator arm 804, it is heated above the critical temperature and isbeginning to resume its original shape. The actuator arm continues torotate in the direction of arrow 830 until it has fully regained itsoriginal shape as shown by actuator arm 805. This embodiment of theactuator assembly and main case may be used in an heat converter enginesimilar to the one described with reference to FIG. 24.

FIGS. 29-31 provide a side view of an aircraft landing gear 290, as maybe embodied in an alternative embodiment of the present invention. Inthese figures, a Shape Memory Spring (SMS) strut 293, a locking latch291, a nitrogen filed shock absorber 297, a retracting strut 295, a tire296, and a locking spring 294 are shown. FIG. 29 illustrates the landinggear 290 in a fully deployed position, FIG. 30 shows the landing gear ina semi-retracted position and FIG. 31 shows the landing gear in a fullyretracted position. The aircraft landing gear 290 in this embodiment maybe employed in the nose of large aircraft and as the main landing gearof lighter aircraft. Exemplary aircraft include airplanes, helicopters,gliders, as well as all others that employ retractable landing gear.

The landing gear 290 may be deployed and locked in an extended positionduring takeoff and landing and may be raised during flight in aretracted, folded, and stowed away position. In this embodiment, thegear may be raised by elongating the SMS strut 293. Then, once thelanding gear 290 is fully retracted, it may be locked in place by thelocking latch 291.

In this embodiment the SMS strut 293 may contain a shape memory alloy(SMA) that expands when heated and contracts when cooled. This shapememory alloy may be sized to develop the required forces necessary toraise the landing gear 290. For example, the cross-sectional area may besized to be able to develop forces greater than two times thosenecessary to raise the landing gear. This level of force is preferred inthis embodiment in order to provide for a safety factor and also inorder to overcome other dynamic forces encountered shortly after takeoffthat may impede the retraction of the landing gear. Similarly, thelength of the shape memory alloy may also be sized such that thedistance of travel of the landing gear is closely correlated to thedistance of maximum expansion of the shape memory alloy. In other words,when the shape memory alloy within the SMS strut 293 is activated itsmaximum distance of expansion may be 20% greater than the maximumdistance required to fully retract the landing gear 290 into theaircraft's fuselage. By considering the maximum length of the SMA, theforces placed on the landing gear, while the SMS strut is active and thelanding gear 290 is in its retracted position, can be controlled.

The SMS alloy, resident within the SMS strut 292, may be heated byvarious methods including passing an electrical current through it, bypositioning it near a heat generating resistor or by passing thermallycharged fluids over and around it. These sources of heat may communicatewith the SMS strut via a shape memory spring strut activation line (notshown). In each case and in the various other plausible methods ofheating the shape memory alloy, as the shape memory alloy is heated itwill expand and, acting through the various members and linkages of thelanding gear, cause the landing gear to retract. Once locked in theretracted position, via a locking hatch or other apparatus, the shapememory alloy may be allowed to cool. Once cooled, the SMA will no longerplace a lifting force on the landing gear. Thus, in the retracted statethe landing gear is maintained in a folded position via the lockinglatch 291. When required, the landing gear 290 may be lowered byunlocking the locking latch 291 and allowing gravitational and lockingspring 294 forces to lower it. The locking latch 291 may be unlocked bypulling on chord 292 although numerous other embodiments are alsoplausible for releasing the landing gear including the use of additionalSMAs, SMSs, locking solenoids or other locking mechanisms. Once releasedand free to move, forces generated by spring 294 may supplement thegravitational forces that will urge the landing gear 290 back into itsfully deployed and locked position.

FIG. 32 is a side view of the landing gear employing an SMS strutactivated by an internal shape memory alloy as installed in a noselanding gear of a light passenger airplane. FIG. 32 contains the nose320 of a light passenger airplane, an SMS strut 325, a nitrogen filledshock absorber 322, a retracting strut 324, and a locking spring 323. Italso illustrates a line of travel of the landing gear with dashed line321. As can be seen in FIG. 32 the line of travel 321 creates an arclike curve in this embodiment.

In addition to the embodiments described above, numerous otherembodiments are also plausible to facilitate the raising and lowering ofaircraft landing gear. For example, the struts and springs may bereconfigured such that the contraction of SMS strut generates therequired forces to raise the landing gear. Furthermore, rather thanusing electrical currents to facilitate the expansion of the strutsother sources of thermal energy may be employed. For example heated airmay be forced across the shape memory alloy in the strut to cause it toexpand in a different embodiment, likewise other fluids, such as wateror oil may be used to heat the shape memory alloy. Moreover, in theseembodiments, a shape memory spring strut activation line (not shown) mayin fluid communication with a pump that urges these compressible andnon-compressible fluids towards the SMA. Once the fluids reach the SMAit will expand in reaction to the thermal energy transferred by thefluid.

FIGS. 33-36 show a landing gear as may be employed in a larger aircraft.FIG. 33 shows the landing gear 330 in a fully deployed position understatic load; FIG. 34 shows the landing gear 330 in a fully deployedposition when the aircraft is airborne; FIG. 35 shows the landing gear330 in a partially retracted position; and, FIG. 36 shows the landinggear 330 in a fully retracted position. As described above, the landinggear contains an SMS strut 331 that generates the lifting force to liftthe undercarriage via the expansion of the shape memory alloy residentwithin it. Like the embodiment described above, the shape memory alloymay be activated through various heat introduction methodologiesincluding electrical current and thermal transfer fluids. In thisembodiment, rather than having a locking mechanism hold the gear in aretracted position the SMS strut is activated throughout the entireflight time to keep the landing gear retracted. Then, when necessary,the shape memory alloy is allowed to cool and, thus, allow the landinggear to retract back down into a locked position.

FIG. 37 is a profile view of a windshield wiper arm as may be employedby a motor vehicle such as a motorcycle, a motor boat, and an automobilein accord with an alternative embodiment of the present invention.During high speeds the airflow over the windshield of a motor vehicle(not shown) may lift the wiper blade 370 off of the glass and therebyreduce the wiper blade's 370 effectiveness. In order to overcome thesehigh speed lifting forces, a downward force, opposing the lifting force,may be generated to hold the wiper blade 370 against the glass.

FIG. 38 is an enlarged view of the circled area in FIG. 37. In FIG. 38the SMS coil 383 is shown in an energized state. Clearly evident in FIG.38 are the wiper arm head 388, pivot pin 385, wiper blade pin 386, wiperarm 381, wiper blade connection 387, reaction arrow 380, rotation arrows3800, force arrow 384, power supply line 382, SMS coil 383, and chassis389.

FIG. 39 also provides an enlarged view of the circled area in FIG. 37.In FIG. 39 the SMS coil 383 is shown in a relaxed state. In FIG. 39, asthe SMS coil 383 is shown in a relaxed state, the reaction arrow 391,rotation arrows 390, and force arrow 392 are opposite those in FIG. 38.

In use, in order to create an additional inward force by the wiper arm381 against the windscreen once the motor vehicle has reached a minimumtarget speed, an electrical voltage may be applied to heating element3810 in order to heat SMS coil 383. Upon being heated, the SMS coil 383,which contains an SMA, will expand and begin to place a force on therocker arm 3820. The direction of this force is illustrated by arrow384. This force causes the rocker arm 3820 to rotate as shown byrotation arrows 3800. As the rocker arm 3820 rotates a reaction forceillustrated by reaction arrow 380 is generated. This reaction forceurges the wiper blades into the windscreen and thus creates a greatercontact force between the wiper blades (not shown) and the windscreen(not shown). Then, as the vehicle slows or the additional forces are nolonger needed, the voltage will be removed and the SMS coil 383 may beallowed to relax back to its original length. No longer exerting a forceagainst the rocker arm 3820, the arm will rotate back to its relaxedposition under biasing forces generated by springs which are not shown.

Rather than using a heating coil 3810 to generate the thermal energythat will facilitate the expansion of the SMS coil 383, other methods ofheating the SMS coil may also be employed. These methods include placinga voltage source directly in contact with the SMS coil 383 and allowingits internal electrical resistance to generate the heat needed toenlarge the coil or forcing thermal conduction fluid over and in contactwith the SMS coil to provide the requisite thermal energy. The thermalconduction fluid may be engine oil pumped from the crank case andregulated by a valve controlled by a processor in the motor vehicle.

FIG. 40 provides an alternative embodiment wherein rather than pushingup on a rocker arm as described above, an SMS coil is placed within thewiper arm head to facilitate the urging of the wiper blades against theglass. In this embodiment, when additional inward force is required tokeep the wiper blade against the glass, the SMS coil 403 may be heatedvia an electrical line, thereby causing it to shrink and create anadditional inward force.

FIGS. 41-42 provide a side view of an automobile power door lockassembly 413 in accord with another alternative embodiment of thepresent invention. These door locking assemblies 413 contain a lockinghead 411, an SMS coil 412, and a bushing 415. The SMS coil 412 may beused to slide the locking head 411 back and forth as indicated by arrows414. The SMS coil 412 may be activated by applying a voltage to it orotherwise heating it. Upon being heated the SMS coil 412 may expand andurge the locking head 411 into one position. Once the heat is removedfrom the SMS coil 412 a biasing force generated by the bushing 415 mayurge the locking head 411 back to its original position. Alternatively,in another embodiment, two SMS coils may be used to move the lockinghead back and forth. In this alternative embodiment an ongoing currentneed not be sustained to maintain the SMS coil in an extended positionto resist the biasing force of the bushing.

FIGS. 43 provides a moveable solar array in accord with anotheralternative embodiment of the present invention. In this embodiment asolar array 431 is pivotably mounted on a frame 433 and is moveable viaSMS coils 432. These SMS coils are in optical communication withfocusing lenses 435. These focusing lenses may be positioned as to focusthe ambient rays of the sun onto the SMS coils 432. These focusinglenses 435 and SMS coils 432 work in unison with each other to rotatethe face of the solar array in conjunction with the movement of the Suncaused by the Earth's rotation. As the Sun moves across the sky its rayswill non-uniformly heat the various SMS coils 432 supporting the solararray. Thus, the SMS coils that receive more of the Sun's rays will beheated to a greater degree and will shrink, thereby pulling the face ofthe solar array towards the Sun. Then, as the Sun moves across the sky,its rays will reach the SMS coils 432 in increasing and decreasingintensities causing the face of the array to rotate and track it acrossthe sky. In short, when one SMS coil 432 receives more light itsdownward forces will increase while another SMS coil 432 will receiveless light, thereby reducing its downward pulling forces.

The focusing lenses 435 may be used to increase the intensity of theradiant energy reaching the coils. Alternatively, when the amount oflight reaching the solar array is large enough, as may be the case inceratin equatorial regions or in outer space, the focusing lenses maynot be needed.

FIG. 44 provides an alternative embodiment wherein the focusing lenses435 have not been employed as may be used in a self-adjusting satellitesolar array.

What is claimed is:
 1. A retractable aircraft landing gear systemcomprising: a shape memory structure, the shape memory structurechangeable from a first length to a second length, the shape memorystructure containing a shape memory alloy; a shape memory structureactivation line coupled to the shape memory structure; a landing gearmoveable from a first position to a second position; and a link couplingthe landing gear to the shape memory structure.
 2. The retractableaircraft landing gear system of claim 1 further comprising: a lockinglatch positioned to engage the landing gear when the landing gear is ina retracted position.
 3. The retractable aircraft landing gear system ofclaim 2, further comprising: a cable connected to the locking latch, thecable slidable from a first position to a second position.
 4. Theretractable aircraft landing gear system of claim 1 wherein the shapememory structure activation line is an electrical line.
 5. Theretractable aircraft landing gear system of claim 1 wherein the shapememory structure encloses the shape memory alloy.
 6. The retractableaircraft landing gear system of claim 1 wherein the shape memorystructure is made with the shape memory alloy.
 7. The retractableaircraft landing gear system of claim 1 wherein the shape memorystructure activation line is a conduit.
 8. The retractable aircraftlanding gear system of claim 7 further comprising: a fluid pumpconnected to the conduit, the pump adapted to force heated fluid throughthe conduit to the shape memory structure.
 9. The retractable aircraftlanding gear system of claim 8 wherein the heated fluid is in a liquidphase.
 10. The retractable aircraft landing gear system of claim 8wherein the heated fluid is in a gaseous phase.
 11. The retractableaircraft landing gear system of claim 8 wherein the heated fluid is oil.12. The retractable aircraft landing gear system of claim 8 wherein theheated fluid is water.
 13. A method of retracting aircraft landing gearcomprising: activating a shape memory alloy, the shape memory alloybeing activated via a shape memory alloy activation line in contact withthe shape memory alloy, the shape memory alloy being moveable from afirst length to a second length, the shape memory alloy linked to alanding gear, the landing gear moveable from a first position to asecond position; and maintaining the landing gear in the second positionafter the activation of the shape memory alloy.
 14. The method of claim13 further comprising: locking the landing gear in predeterminedposition.
 15. The method of claim 13 wherein the shape memory alloy isactivated by raising its temperature with thermal energy carried by afluid.
 16. The method of claim 13 wherein the shape memory alloy isactivated by raising its temperature with thermal energy cleated throughresistance to electrical current flow.
 17. The method of claim furthercomprising: locking the landing gear in a predetermined position; andde-activating the shape memory alloy.
 18. The method of claim 17 furthercomprising: unlocking the landing gear by opening a locking latch. 19.The method of claim 13, wherein the fluid is oil.
 20. The method ofclaim 13 wherein the fluid is in a gaseous phase.